Hi, Here is the code, which I would like to understand.
>>> l=['a','b','c'] >>> bm=dict.fromkeys(l,['-1','-1']) >>> u={'a':['Q','P']} >>> bm.update(u) >>> bm {'a': ['Q', 'P'], 'c': ['-1', '-1'], 'b': ['-1', '-1']} >>> for k in bm.keys(): bm[k].append('DDD') >>> bm {'a': ['Q', 'P', 'DDD'], 'c': ['-1', '-1', 'DDD', 'DDD'], 'b': ['-1', '-1', 'DDD', 'DDD']} I was expecting appending DDD to happen once for 'c' and 'b'. {'a': ['Q', 'P', 'DDD'], 'c': ['-1', '-1', 'DDD'], 'b': ['-1', '-1', 'DDD']} -- https://mail.python.org/mailman/listinfo/python-list